Performance of a complex psychomotor task, the Multiple Task Performance Battery (MTPB), has been shown to reliably suppress smoking. Performance of the same task has also been shown to produce sustained, non-habituating increases in blood pressure. Pilot observations suggest that these task-elicited blood pressure responses are potentiated by the administration of caffeine and/or nicotine prior to task performance. These observations suggest that nicotine and caffeine may have potent effects on task-elicited cardiovascular reactivity which are not discerned when simply looking at drug-elicited changes in cardiovascular levels. The findings that l) complex task performance is associated with suppressed smoking as well as elevated blood pressures, while 2) performance of more relaxing or unstructured tasks is associated with increased smoking and with negligible increases in blood pressure, suggest that elicited cardiovascular responding may be associated with activity-induced or activity-suppressed smoking. In the first experiment of this proposal, the effects of several doses of nicotine and caffeine on a variety of MTPB-elicited cardiovascular responses will be studied. In the second experiment, the interaction of subtask type and incentive with the presence or absence of nicotine and caffeine will be investigated. The purpose of the first two studies is to characterize as fully as possible the dose and task-dependent effects of nicotine and caffeine modulation on cardiovascular reactivity. In a third study, findings from the first two experiments will provide the basis for analysis of relevant activity sequences for subjects participating in long-term residential experiments. The sequences will include activities which are associated with differing degrees of elicited change in cardiovascular state both with and without caffeine and nicotine administration. The purpose of this third experiment is to investigate the relationship between activities associated with differing degrees of cardiovascular reactivity and ad libitum smoking and coffee use. The findings of the three proposed experiments are directly relevant to "arousal"-based theories of substance use and, in addition, provide basic information on the effects of nicotine and caffeine on cardiovascular reactivity, a largely unexplored area.